The present invention relates to an apparatus and a method for forming a coating layer, particularly to a die set and a method for forming a coating layer of multiple stripes composed of three materials A, B and C adjacent to one another in a repeated ABCABC or A_B_C_A_B_C pattern. The symbol, xe2x80x9c_xe2x80x9d, implies that there is no coating between two adjacent stripes.
The die coating technique has been developed since nineteen fifties. This technique was first applied to form a large-area continuous coating, and was modified to form various function coatings in electronic and information industries nowadays. Among them a stripe coating technique was used to form a coating layer of multiple stripes on a substrate, which involves die design and precision coating techniques. The stripe coating technique not only can be utilized to produce a conventional product such as an adhesive tape, but to fabricate advanced electronic devices such as laser printers, and Li batteries.
U.S. Pat. No. 4,106,437 discloses an apparatus for multiple stripe coating of a web with liquid coating composition which is comprised of a hopper having a pair of spaced lips and a pair of shims mounted in face-to-face arrangement within the hopper and positioned between the spaced lips. One of the shims is provided with a plurality of open-ended channels while the second shim is equipped with a plurality of projecting portions, corresponding in width and location to the desired stripes, which are in alignment with the open-ended channels and project beyond the open ends thereof. The apparatus is capable of carrying out multiple stripe coating of a web at high speeds and with a high degree of precision in regard to stripe width and registration.
U.S. Pat. No. 4,324,816 discloses extrudable materials which exhibit a decrease in viscosity as the shear rate is increased, such as magnetic dispersion striping materials, and are suitable for extrusion coating in the form of a narrow stripe. The stripe has predetermined uniform cross-sectional dimensions including substantially uniform thickness, and is coated onto a moving web by means of a die maintained in a predetermined spaced relation with the web. The die has two or more bores through which the extrudable material is extruded in columns onto the moving web to form the stripe thereon.
Japanese patent publication No. 7-136568 A discloses a method for simultaneously forming continuous coating surfaces of the same thickness free from joints in the transverse direction of a band-shaped material by segmenting a coating liquid passage consisting of manifold parts and a slit part in a transverse direction and supplying different kinds of coating liquids in the respective segmented passages.
Japanese patent publication No. 7-195015 A discloses methods for producing multiple stripe coating product. To easily control the coating width of a coating solution and to make accurate stripe coating possible, a liquid-permeable sheet is placed in a slot of a coating die to discharge a coating solution.
Japanese patent publication No. 8-038972 A discloses methods for producing multiple stripe coating product, in which continuously coating a stripe pattern consisting of plural colors on a belt-like material with one coating process and also easily changing the width of a stripe are made possible. A manifold is provided in the inside of a metallic material apart from a slot part for discharging a coating material. A plurality of through-holes communicated with the slot part, and a plurality of coating liquid feed-ports communicated with a coating liquid feed device at the outside of a die main body are formed on the manifold.
Japanese patent publication No. 8-099056 A discloses methods for forming a coating film in a stripe pattern with no fluctuation width and thickness by projecting a front block more than a back block toward a base material and forming jetting-out holes for a coating material in the flat face of the back block. In this prior art, a nozzle is composed of a front block positioned in the upper stream side in a base material running direction and a back block positioned in the down stream side. The front block of the nozzle is projected toward the base material side as compared with the back block. When a base material is moved along the surface of the nozzle composed in this way, the base material moves along the curved face of the front block and continuously moves above the back block of the nozzle in which jetting-out holes for a coating material are formed. Consequently, a coating film in a stripe pattern with no fluctuation of width is formed on the surface of the base material by coating.
When a coating product of multiple stripes is made, interfaces of different coating solutions will be affected by coating thickness thereof and physical properties of coating solutions, such as the viscosity and the surface tension. These will result in a tendency that the borders of the coating solutions extend outward and become thin, and thus a coating layer of inferior uniformity and low interfacial quality is formed.
In the aforesaid prior art methods for forming a coating in an ABAB pattern, it is difficult to ensure a definite and precise interface between two adjacent coating solutions A, B and even harder to generate an intermediate layer of multiple stripe in a multiple coating layer structure. Among them Japanese patent publication Nos. 7-136568, 8-038972 and 8-099056 have great disadvantages in non-uniform width of stripes and ambiguous interfaces of coating solutions A, B, because the two coating solutions are contacted with each other outside the die set. Moreover, none of the aforesaid prior art references discloses or suggests a technique for forming a coating layer of multiple stripes composed of three materials A, B and C adjacent to one another in a repeated ABCABC or A_B_C_A_B_C pattern.
The color filter used in the flat panel display system, such as STN-LCD and TN-LCD, was produced by optical exposure and development techniques, wherein R (red), G (green) and B (blue) stripes having a width of about 100 micrometer were fabricated one at a time. Accordingly, same tedious procedures have to be repeated trice. In the fabrication of a plasma display panel (PDP), R, G and B stripes having a thickness of 100 micrometers and a width of 50 micrometer were formed on a glass substrate by powder coating. In general, the powder coating was repeated about 10 times to meet the thickness requirement.
An object of the present invention is to provide a device and a method for simultaneously forming multiple stripes of repeated coating liquids composed of three materials A, B and C adjacent to one another in an alternating ABCABC pattern with distinct interfaces between adjacent strips of any two coating liquids.
Alternatively, multiple stripes of repeated coating liquids in an alternating A_B_C_A_B_C pattern is formed in the present invention.
In order to accomplish the object of the present invention a die set for preparing ABCABC or A_B_C_A_B_C repeated multiple-stripe coating composed of three different liquids A, B and C constructed according to the present invention comprises a B-liquid die, a B-liquid shim, a guide shim, an A-liquid shim, a guide die, a C-liquid shim and a C-die, wherein:
said guide die comprising a plurality of spaced C-liquid distribution blocks projecting from a first side thereof by the same height, a C-liquid blocking block projecting from a second side thereof opposite to said first side, a plurality of C-liquid distribution passages, each of said plurality of C-liquid distribution passages connecting said first side and said second side of said guide shim, an A-liquid groove on said first side of said guide shim, and an A-liquid inlet communicating with said A-liquid groove;
said guide shim comprising a plurality of spaced B-liquid distribution blocks projecting from a first side thereof by the same height, a B-liquid blocking block projecting from a second side thereof opposite to said first side of said guide shim, a plurality of B-liquid distribution passages, each of said plurality of B-liquid distribution passages connecting said first side and said second side of said guide shim;
said A-liquid shim is clamped between said first side of said guide die and said first side of said guide shim, wherein said A-liquid shim has a thickness equal to the height of said C-liquid distribution blocks and equal to the height of said B-liquid distribution blocks, wherein said C-liquid distribution blocks and said B-liquid distribution blocks are alternately adjacent to each other, so that a plurality of spaced B-C-liquid distribution blocks are formed, wherein said A-liquid shim has a shape enclosing said A-liquid groove and said B-C-liquid distribution blocks, so that an A-liquid fed to said A-liquid inlet will fill said A-liquid groove and flow around said B-C-liquid distribution blocks and in a slot formed between said first side of said guide die and said first side of said guide shim toward a direction away from said A-liquid groove to exit from said die set;
said B-liquid die comprising a B-liquid inlet and a B-liquid groove communicating with said B-liquid inlet;
said B-liquid shim is clamped between said second side of said guide shim and said B-liquid die, wherein said B-liquid shim has a thickness equal to a projecting height of said B-liquid blocking block, wherein said B-liquid shim has a shape enclosing said B-liquid groove and said B-liquid blocking block, and intimately joining to said B-liquid blocking block, so that a B-liquid fed to said B-liquid inlet will fill said B-liquid groove and flow into said plurality of B-liquid distribution passages to exit from said first side of said guide shim;
said C-liquid die comprising a C-liquid inlet and a C-liquid groove communicating with said C-liquid inlet; and
said C-liquid shim is clamped between said second side of said guide die and said C-liquid die, wherein said C-liquid shim has a thickness equal to a projecting height of said C-liquid blocking block, wherein said C-liquid shim has a shape enclosing said C-liquid groove and said C-liquid blocking block, and intimately joining to said C-liquid blocking block, so that a C-liquid fed to said C-liquid inlet will fill said C-liquid groove and flow into said plurality of C-liquid distribution passages to exit from said first side of said guide die.
Preferably, each of said plurality of C-liquid distribution blocks of the die set of the present invention has an inverted-U shape and comprises a head and two legs, wherein said two legs point to a direction same as the direction of said A liquid exiting from said die set, wherein each of said plurality of C-liquid distribution passages has an outlet between said two legs of said C-liquid distribution block; each of said plurality of B-liquid distribution blocks has an inverted-U shape and comprises a head and two legs pointing to a direction same as the direction of said A liquid exiting from said die set, wherein each of said plurality of B-liquid distribution passages has an outlet between said two legs of said B-liquid distribution block.
Preferably, said two legs of said C-liquid distribution block have a length equal to that of said two legs of said B-liquid distribution block.
Preferably, the length of said two legs of said C-liquid distribution block and the length of said two legs of said B-liquid distribution block are not long enough to reach an edge of said die set, so that said A liquid, said B liquid and said C liquid will join at positions near ends of said two legs of each of said plurality of B-liquid distribution blocks and each of said plurality of C-liquid distribution blocks, and form an ABCABC pattern, when said A liquid, said B liquid and said C liquid are fed to said A-liquid inlet, said B-liquid inlet and said C-liquid inlet, respectively.
Alternatively, the length of said two legs of said C-liquid distribution block and the length of said two legs of said B-liquid distribution block are long enough to reach an edge of said die set, so that said A liquid, said B liquid and said C liquid will not join inside said die set, and will form an A_B_C_A_B_C pattern on a substrate passing underneath said edge of said die set, when said A liquid, said B liquid and said C liquid are fed to said A-liquid inlet, said B-liquid inlet and said C-liquid inlet, respectively.
The present invention also discloses a method for forming multiple stripes of repeated coating liquids composed of three materials A, B and C on a substrate by using the die set of the present invention, which comprises the following steps:
a) feeding said A liquid, said B liquid and said C liquid into said A-liquid inlet, said B-liquid inlet and said C-liquid inlet, respectively; and
b) continuously passing a substrate under said slot formed between said first side of said guide block and said first side of said guide shim to allow said A liquid, said B liquid and said C liquid to adhere to said substrate forming an ABCABC pattern or A_B_C_A_B_C pattern.
The method of the present invention may further comprises changing said thickness of said A-liquid shim as well as the height of said C-liquid distribution blocks and the height of said B-liquid distribution blocks, or changing flow rates of said A liquid, said B liquid or said C liquid, to adjust thickness of said A liquid, said B liquid or said C liquid adhering to said substrate.
Preferably, said A liquid, B liquid and C liquid have red color, green color and blue color, respectively.
The present invention also provides a coated product having ABCABC repeated multiple-stripe coating, which comprises a flat substrate, and ABCABC repeated multiple-stripe coating composed of three different liquids A, B and C on a surface of said flat substrate, wherein said ABCABC repeated multiple-stripe coating is formed simultaneously and every two adjacent stripes thereof contact each other, wherein each stripe of said ABCABC repeated multiple-stripe coating has a width less than 200 micrometers.
Preferably, each stripe of said ABCABC repeated multiple-stripe coating has a width of 20 micrometers to 150 micrometers, and a thickness of 1 micrometer to 50 micrometers.
Preferably, said A stripe, B stripe and C stripe of said ABCABC repeated multiple-stripe coating have red color, green color and blue color, respectively.
Alternatively, the present invention provides a coated product having A_B_C_A_B_C repeated multiple-stripe coating, which comprises a flat substrate, and A_B_C_A_B_C repeated multiple-stripe coating composed of three different liquids A, B and C on a surface of said flat substrate, wherein said A_B_C_A_B_C repeated multiple-stripe coating is formed simultaneously, and every two adjacent stripes thereof do not contact each other, wherein each stripe of said A_B_C_A_B_C repeated multiple-stripe coating has a width less than 200 micrometers.
Preferably, each stripe of said A_B_C_A_B_C repeated multiple-stripe coating has a width of 20 micrometers to 150 micrometers, and a thickness of 1 micrometer to 50 micrometers.
Preferably, said A stripe, B stripe and C stripe of said A_B_C_A_B_C repeated multiple-stripe coating have red color, green color and blue color, respectively.
The present invention can be more fully understood by reference to the following detailed description and accompanying drawings.